Flat gasket and method for the production thereof

ABSTRACT

The invention relates to a flat gasket comprising at least one metallic layer, in which at least one continuous opening is made, whereby the or at least one metallic layer ( 1 ) is provided, at least in areas, in the shape of an undulated and/or serrated profiling ( 2 ) around the continuous opening(s).

[0001] The invention relates to a flat gasket having at least onemetallic layer in which respectively at least one port is formed and amethod for the production thereof. The single or also multi-layer flatgasket can be formed and used in particular as cylinder head gasket butalso for other faces to be sealed together, such as the most variedflange gaskets.

[0002] In order to increase and safeguard the sealing effect of such ametallic flat gasket over a fairly long period of time, it is normal toform a bead, which completely encloses this port as a rule, around themost varied ports by corresponding shaping at least of one of the layersof such a flat gasket.

[0003] Such a bead can however only fulfil the function as long as acertain degree of elasticity is maintained in the bead region, which asa rule cannot be maintained without additional aids with which acomplete plastic deformation is prevented. For this purpose normallydeformation limiters are used for the beads. Such deformation limitersare known in the most varied of embodiments and are normally designatedalso as “stoppers”. Thus, deformation limiters can be obtained bybending over one of the metallic layers or by additional elements.

[0004] In DE 298 04 534, an example of such a deformation limiter in theform of a grooved region which is formed in a metallic layer isdescribed. Such a grooving is produced in the metallic layer by cold orhot shaping. The grooving is thereby dimensioned with respect to thethickness of the metallic layer or respectively also taking into accountspecific installation conditions of such a gasket in such a manner thatthe grooved region represents a corresponding thickness increase.

[0005] However, only a limited influence can be achieved on the desiredproperties with such a grooving as deformation limiter and in particularthe variation with corresponding adaptation to the most varied of usageconditions, which can also be locally different on a flat gasket, isonly possible in a conditional manner and in a restricted form.

[0006] In each of the suitable production methods, a change in the metalin this region occurs, independently of whether a cold or respectively ahot forming has been implemented which must be taken into account forsuch flat gaskets at least in the choice and shaping of the flatmaterial.

[0007] In particular in the formation of such a grooving by pressinginto the cold metal, a corresponding wear and tear on the pressing tooloccurs so that the costly tools must be replaced at more or less largeintervals.

[0008] In addition, the grooves cannot be introduced into the metalliclayer reproducibly at any depth and at any density.

[0009] It is hence the object of the invention to make available a flatgasket and also a method for the production thereof having at least onemetallic layer which is better adapted to the locally occurringinfluences and with which such a flat gasket can be producedeconomically.

[0010] According to the invention, this object is achieved by a flatgasket according to claim 1 or a method according to claim 29.Advantageous embodiments and developments of the invention are producedwith the features contained in the subordinate claims.

[0011] In the case of the flat gasket according to the invention whichcan comprise one or respectively also a plurality of metallic layersdisposed one above the other, there is inserted, in contrast to thealready mentioned, known grooving, a profiling in at least the onemetallic layer or in one of the metallic layers at least in regionsaround the one or also more ports, in particular in ports for combustionchambers in cylinder head gaskets. Such a profiling can be formedthereby in an undulating form and/or in a serrated form, this form beingimpressed into the respective metallic layer.

[0012] The term undulating in the present invention includes alsoembodiments which deviate from a sinusoidal wave. The undulation canaccordingly be flattened also into crests and troughs and have forexample straight sides. Trapezoidal embodiments also fall within theterm wave of the present invention.

[0013] The profiling is formed preferably at least in regions around theport(s), as far as possible adapted to its external contour. Ideally,such a profiling has three and more wave crests or three and more teethon each side of the gasket. In this case, a good sealing behaviour isachieved even without filling or coating of the profiling.

[0014] If a serrated profiling is impressed, it is expedient tocorrespondingly round off the tips of the individual teeth which pointalternately in the direction of both sealing faces. In the case of awave profile, this is of course not required. In both cases, therespective wave crests or wave troughs can however also be flattened outor smoothed, as a result of which a particularly effective seatingsurface of the stopper on the adjacent sealing layers is formed.Advantageously, the heights of the wave crests or of the individualteeth, i.e. the amplitude, are not definitely constant across the entireprofiling but, in specific circumferential regions around a port, takinginto account the respective geometric shape, can be of a different size.In the same way, the spacings of wave crests or teeth relative to eachother can also be varied.

[0015] Different amplitudes of the teeth or wave crests and/or differentspacings between the individual teeth or wave crests and also differentradii of the waves, proceeding at an increasing spacing from the edge ofthe respective port, can be set in order to be able to locally influencein particular the elasticity and the resilient rigidity in a targetedmanner. A plastic forming of one region of such a profiling can also bepermitted thereby in a defined manner or be undertaken already beforeinstallation of such a flat gasket.

[0016] Furthermore the transition region between wave troughs and wavecrests or between teeth situated adjacent to each other on oppositelysituated sides can have a lower material thickness than the wavecrests/wave troughs or teeth. By suitable impressing during productionof the profiling (edge swaging) the material thickness can also beprofiled in this manner and the properties of the profiling can beadapted to the respective specific conditions. It is also possible toswage not the edges but rather the crests or troughs. A so-called radiusswaging then leads to a thickening of the edges.

[0017] It can already suffice to form a profiling around the ports, theperiod length of which is =1. This means that the profiling comprisesmerely two wave crests or two teeth which are formed in respectivelyopposed directions. Of course, a larger number of wave crests,advantageously three or more, can however also be used.

[0018] It is particularly preferred if the profiling is used asdeformation limiter for additionally formed beads.

[0019] The possibility therefore exists with a single layer gasket offorming a profiling according to the invention at least on one side ofone such bead, of course the possibility also being offered of anarrangement of profilings on both sides. Preferably the profiling isdisposed on the combustion chamber side. In the case where the profilingfunctions as deformation limiter and is adjacent to a bead, theformation of the undulation, i.e. the profile height (amplitude) and thespacing of the wave crests (period) is coordinated to the bead. Theprofiling, i.e. in particular the amplitude of the wave, must be smallerthan the extension of the bead (see for example FIGS. 4 and 6).

[0020] The profiling can however be formed even in the case of amulti-layer seal in one layer and the bead in an adjacent layer.

[0021] According to the invention, a flat gasket can comprise also atleast two metal layers which both have an undulating or serratedprofiling. These profilings can be placed one above the other.Advantageously, the profilings in the two layers are designeddifferently with respect to length, depth and/or radius of therespective undulation (amplitude, profile height and radius). If twodifferently designed undulating beads are compressed such in the engine,directly in contact with each other, then the relative movement of eachof the undulating beads is dependent upon the respective wave structure.The difference of the relative movement of the two profilings can beused as elastic spring element for sealing with a high tensioning force.Thus in one of the metal sheets there is no need for the entire bead andnevertheless the tensioning force of an entire bead can be exceeded.

[0022] Furthermore, the layer, which has the profiling, can bereinforced in the region of the profiling by at least one further layer,for example a ring, advantageously with the width of the profiling. Thislayer or this ring can grip round the profiled layer also along thecircumferential edge of the port at least in regions and form there aso-called folded stopper. The reinforcing layer or respectively thereinforcing ring can have the same profiling and consequently bothprofilings can abut against each other in a form fitting manner. Herealso, the amplitude, period and radius of the profiling of thereinforcing layer or respectively of the reinforcing ring can however bevaried along the circumferential edge and/or perpendicularly to thecircumferential edge of the port. If the period, amplitude and radiusdiffer from each other on various layers of adjacently disposedprofiling, then the sealing behaviour can be specifically influencedfurther in this manner.

[0023] The stopper (layer or ring) can be connected to the undulatingstopper by means of any optional welding methods. By means of thiswelded-on stopper, a variable projection is achieved which at the sametime contains an elastic portion. The choice of thickness of theadditional stopper makes it possible to adapt the gasket in the stopperregion to the engine conditions. Thus, very high and robustconstructions can be achieved, for example for diesel engines even inthe sphere of lorries.

[0024] In contrast to conventional flat gaskets with deformationlimiters, bending-over or beading of layers of the flat gasket oradditional elements in order to produce deformation limiters can bedispensed with and consequently the production costs can be reduced.

[0025] In a preferred embodiment, an adequate and durable sealing effectof a flat gasket according to the invention with corresponding profilingcan also be achieved if the beads surrounding the ports have beendispensed with. In this case, the entire function, which has beenachieved previously by the bead with deformation limiter, is achievedsolely by means of the profiling.

[0026] For this purpose, the profiling of one or more layers can bevirtually optimised by corresponding shaping and dimensioning in thatthe elasticity, the resilient rigidity and also a specifically desireddegree of plastic deformation can be set in the various regions of sucha profiling. Hence, it is possible as mentioned already initially,correspondingly to vary the spacings of the individual wave crests orteeth from each other and/or their heights and/or the radii of theindividual waves. For example the region of a profiling pointing in thedirection of a port can also have smaller spacings of the wave crests orteeth from each other than the further removed regions. In the justmentioned region, the elasticity is consequently less than in thedensely packed regions of such a profiling. The spacings and/or heightscan however also be successively enlarged, starting from the externaledge of a port.

[0027] The densely packed regions of a profiling have a smallerelasticity and, in contrast thereto, are plastically deformable in alimited manner and this region can accordingly take over if necessarythe function of a deformation limiter.

[0028] Furthermore, a variation in the number of wave crests or troughsor teeth, in the sheet thickness, in the heights or form, in particularof the radii of the wave crests/wave troughs or teeth and their spacingand the like can also be produced along the circumference of the port,for example of a cylinder boring.

[0029] The metal layers, in which the profiling is introduced, can alsobe formed differently with respect to their upper side and underside,i.e. to both sides, which are orientated in the installed state forexample towards the cylinder head or cylinder block, for example withrespect to height and form of the wave crests, wave troughs and the likeso that the stopper can accomodate the different properties of forexample cylinder head and cylinder block which can be manufactured fromdifferent materials.

[0030] The layer which has the profiling can furthermore be formed fromcold deformable steel, for example a maraging steel, such as Zapp VACL180T which hardens by tempering for example to 300° C.

[0031] The rigidity of specific regions of a profiling can also beincreased by means of webs which are disposed and formed between theindividual adjacent wave crests or teeth. Such webs can be used in aserial or else offset arrangement. The webs can however also be presentonly in one region which is disposed at a greater spacing from therespective port.

[0032] The profiling to be inserted according to the invention can beformed in the most varied of metallic materials, i.e. also in variousspring steel materials, an even greater elasticity and consequently animprovement in the sealing effect being able to be achieved with springsteel over a long period of time.

[0033] The flat gasket according to the invention can be developed inaddition in that materials known per se are applied on at least one sideof a metallic layer. Suitable materials, for example elastomers, arementioned for example in DE 198 29 058, DE 199 28 580 and DE 199 28 601,the disclosure content of which is referred to in its entirety.

[0034] Such a filler is then present at least also in regions and inparts of the profiling and the elasticity and resilient rigidity can beinfluenced by means of the respective elastomer. A further influentialdimension, when using such fillers, is in addition to their arrangementalso the respective filling level in the profiling. This means that thewave troughs of such a profiling or the intermediate spaces between theteeth of a serrated profiling can be filled completely but alsopartially so that, in addition to the already mentioned local influenceon elasticity and resilient rigidity, the damping properties can beinfluenced also in various ways.

[0035] The filling level can be changed with an increasing spacing fromthe edge of the ports. It can however also be varied across thecircumference of the respective ports.

[0036] The flat gaskets according to the invention, irrespectively ofwhether they are intended to be produced in a single layer ormulti-layer with or without additional filler, can be produced with fewtechnologically, easily controllable operational steps and consequentlyin a particularly economical manner.

[0037] Due to the most varied of options with respect to the shaping anddimensioning of the profiling, properties can be set specificallylocally.

[0038] The possibility also exists of using a combination of undulatingand serrated forms within one profiling.

[0039] Attention should be drawn not least to the fact that, in the caseof a serrated profiling, the correspondingly formed layer is bentcorrespondingly in cross-section and the individual teeth are notimpressed into the material, as is the case in the grooving known in thestate of the art. This applies of course analogously to an undulatingprofiling also.

[0040] In the case of the flat gaskets according to the invention, nolocal hardening occurs in the metal. In addition, a reduced warping isachievable. The profilings can also be formed with hard spring steels.

[0041] The invention is intended to be explained in detail subsequentlywith reference to embodiments which show;

[0042]FIG. 1 a sectional representation through a part of a flat gasketaccording to the invention in which an undulating profiling forms adeformation limiter for a conventional bead;

[0043]FIG. 2 a part of a three-layer flat gasket with two externallysituated beaded layers and

[0044]FIG. 3 a part of a further example of a flat gasket according tothe invention with a variably formed profiling;

[0045]FIG. 4 a further example of a flat gasket according to theinvention;

[0046]FIG. 5 four further examples of single layer flat gasketsaccording to the invention;

[0047]FIG. 6 in total eight further examples of flat gaskets accordingto the invention;

[0048]FIG. 7 four further examples of flat gaskets according to theinvention;

[0049]FIG. 8 an embodiment in which the profiling is formed as atrapeze, and

[0050]FIG. 9 an embodiment in which the profiling is formed as aradius-swaged bead.

[0051] In the example of a single layer flat gasket according to theinvention, illustrated in FIG. 1, a bead 3 is formed in the metalliclayer 1 and, in the direction of a port, not shown here, there abuts anundulating profiling 2, the wave crests and wave troughs of which aredisposed regularly and consequently the wave crests also have a constantprofile height and constant spacings from each other. The profiling 2fulfils in this case, in addition to the function of a deformationlimiter for the bead 3, also a sealing function in addition due to theachievable elastic properties.

[0052] Here as in the description of the following Figures,corresponding reference numbers are used for corresponding elements.

[0053] The resilient characteristics and consequently also theelasticity can, in a non-illustrated form, be influenced by filling theintermediate spaces between the adjacent wave crests of the profiling 2,for example with elastomer and at different filling levels. Of course,the intermediate spaces between the wave crests can also be filledcompletely with an elastomer.

[0054] In a non-illustrated form, a corresponding profiling 2 can beformed also on the other side of the bead 3.

[0055] A three-layer flat gasket is shown in FIG. 2. In this example,beads 3 are again formed in the two externally situated layers 1′ of theflat gasket and a likewise undulating profiling 2 is presentcorrespondingly in the central layer 1. Of course, the statements withrespect to options for influencing properties, which have been madealready in FIG. 1, also apply analogously to this example.

[0056] In FIG. 3, once again a single layer metal flat gasket is shown,the formation of an additional bead 3 having been dispensed with in thisexample. The bead function in this example can also be fulfilled by thecorrespondingly formed profiling 2. The spacings and profile heights ofthe individual wave crests of the profiling 2, starting from thedirection of the edge of a port, not shown here, are thereby smallerthan is the case in the regions of the profiling 2 at a greater spacingfrom the port. The correspondingly more closely situated regions aremore rigid and can be deformed plastically only slightly, if at all.

[0057] The region, which is further away from the port, has a greaterperiod length, the spacings of the wave crests from each other arecorrespondingly greater, the latter also applying to the profile heightof the wave crests in this region. Consequently, a higher elasticity andlower rigidity is present in this region of the profiling 2. In theinstalled, i.e. pre-stressed state of such a flat gasket, the region ofthe profiling 2 with the greater spacing from the port can then fulfil adeformation limiter function for the pre-positioned region of theprofiling 2 due to the mentioned properties.

[0058] The profiling can be obtained in its shape by using acorrespondingly formed and dimensioned impressing tool already duringforming. However the possibility exists of producing such a shaping ofthis region in a second technological operational step by correspondingswaging and pressing.

[0059] It is advantageous if the firstly obtained profiling 2 isplanished subsequently completely or in regions so that in the planishedregion the profile height is reduced again. For this purpose, one or twostamps with flat pressing faces orientated parallel or diagonally at anangle towards the surface of the metal layer 1 can be pressed onto theregion to be planished. During planishing, the metallic layer 1, inparticular at the edges of the profiling 2 should be braced. Due to thesubsequently implemented planishing, the rigidity and the hardness ofthe profiling 2 can be increased and consequently also the rigidity of aflat gasket according to the invention.

[0060] Since in the examples of flat gaskets according to the invention,illustrated in the FIGS. 1 to 3, representative limits are set by thechoice of sectional representations, it should be indicated that theprofiling, as seen across the circumference, i.e. in various radialaxes, can be shaped and dimensioned differently. Thus the possibilityexists of varying the number of successively disposed wave crests orteeth across the circumference and/or of undertaking a correspondingchange in the spacings and profile heights of the profiling.

[0061]FIG. 4 shows a further example of a single layer flat gasket,having a single metal layer 1 in which a bead is impressed. Anundulating stopper region 2 is disposed between the bead 3 and the portsituated on the right. Said stopper region has in total three wavecrests and three wave troughs. Underneath this stopper region, a ring 8is welded-on along the circumferential edge of the port, said ringhaving the same profiling as the metal layer 1 and abutting against thelatter in a form fit. In the ring 8, a profiling 2′ with three wavecrests and three wave troughs is formed likewise as a result. With anadditional stopper ring 8 of this type, the flat gasket according to theinvention can be adapted to variable engine geometries or engineconditions in which both the width and the material thickness of themetal ring 8 are chosen correspondingly.

[0062]FIG. 5 shows details of four further flat gaskets comprisingrespectively one single layer. This individual layer can equally be acomponent of a multi-layer gasket. The illustrated flat gaskets in FIG.5A and 5C have the same material thickness, whilst the flat gasketsshown in FIGS. 5B and 5D have a greater layer thickness. In contrast,the undulations in the stopper region 2 in FIGS. 5A and 5B have asmaller radius of curvature than in the flat gaskets in FIGS. 5C and 5D.It is shown here consequently that, by means of a different materialthickness of the layer and also by means of different forming of theprofiled regions 2 of the layer 1, greater clearance for adaptationpossibilities of this stopper 2 to various engine characteristics areoffered.

[0063] Furthermore, in all the profiled regions 2 illustrated in FIG. 5,respectively the material thickness in an intermediate region 6 betweena wave crest 7 and an adjacent wave trough 7 is smaller than in theregion of the wave troughs or wave crests 7. As a result, the elasticbehaviour of the stopper regions 2 can also be varied.

[0064]FIG. 6 shows in total eight different variants of flat gasketsaccording to the invention. FIG. 6A shows an in total six-layer flatgasket comprising six metal layers 1 a to 1 f. In the layer 1 b and inthe layer 1 e, two profiled stopper regions 2 b or 2 e are formedrespectively as deformation limiters for the beads 3 a, 3 c, 3 d or 3 fformed in the layers 1 a, 1 c, 1 d and 1 f.

[0065] A corresponding five-layer gasket is illustrated in FIG. 6B inwhich once again two layers are provided with profiled stopper regions.In this case, an intermediate layer 1 c is interposed between the twoupper layers 1 a and 1 b and the two lower layers 1 d and 1 e, saidintermediate layer having neither a bead nor being profiled.

[0066] Three-layer flat gaskets are illustrated in FIGS. 6C to 6E, theintermediate layer 1 b having a step 4 in FIG. 6D. A profiled stopperregion 2 c, which functions as stopper for the bead 3 c, is adjacent tothe step 4 on one side. As a result of the fact that an offset isprovided in the layer 1 b which offset is orientated away from thestopper region 2 c, the elastic stopper function of the profiled region2 c across the layer 1 b which is offset in the profiled region of thelayer 1 c is used also for the bead 3 a in the layer 1 a. FIGS. 6F and6G show two-layer flat gaskets in which a profiled region 2 b is formedin respectively one of the gasket layers. Said region serves as stopper(deformation limiter) for the beads 3 b in FIG. 6F or the beads 3 a and3 b in FIG. 6G.

[0067]FIG. 6H shows in turn a four-layer flat gasket, respectively onebead 3 a and 3 d facing towards each other being formed in both externallayers 1 a and 1 d. These two external layers 1 a and 1 d enclose twofurther layers 1 b and 1 c which have no bead. They have however regions2 b and 2 c which are chosen laterally adjacent to the beads 3 a and 3d, said regions having the same profiling and abutting against eachother in a form fit. These two layers 1 b and 1 c form a stopper(deformation limiter) in the profiled region for the beads 3 a and 3 dby means of the parallel extending profiled regions 2 b and 2 c. Due tothis arrangement of two parallel profiled regions, the sealing effectand the deformation limiting can be adapted to the respective conditionsof the engine to be sealed.

[0068] If alternatively, in the gasket according to FIG. 6H for the twolayers 1 b and 1 c in the region of the undulating profilings 2 b and 2c, different lengths, depths and/or a different radius of theundulations is used in the two profilings, then the extended length ofthe two profilings is different when compressed in the engine for thetwo layers 1 b and 1 c. This difference of the relative movement leadsto narrow annular contacts between these two profilings 2 b and 2 c.Such an arrangement can be used for sealing as an elastic spring elementwith a high tensioning force which can exceed the tensioning force ofone complete bead. In this case, a purely two-layer gasket can also beused, only the two gasket layers 1 b and 1 c of the four gasket layersin FIG. 6H forming the gasket together.

[0069]FIG. 7 shows here further examples of flat gaskets according tothe invention. FIG. 7A thereby shows a flat gasket which has twometallic layers 1 a, 1 b. The layer 1 b is provided with a bead 3against which a profiled region 2 abuts directly adjacent to the port.The layer 1 a adjacent to the layer 1 b is not profiled, but gripsaround the layer 1 b along the circumferential edge of the port and thusforms a stopper ring 9 on the opposite layer 1 b. Hence the deformationlimiting stopper effect is produced from the cooperation of theprofiling 2 with the stopper 9.

[0070] In FIG. 7B, a corresponding two-layer flat gasket is illustratedas in FIG. 7A. The regions of the layer 1A directly adjacent to theprofiled region, designated here with 2B, of the layer 1 b, are providedin the same way with a profiling 2 a or 2 c so that the layer 1 a abutsin a form fit against the profiled region 2B of the layer 1 b on bothsides.

[0071]FIG. 7C shows an arrangement as in FIG. 7A, however the layer 1 abeing provided not as a whole-surface metallic layer, but only asstopper ring 8 in the region of the profiling 2 of the metallic layer 1.Once again the stopper 8 grips around the layer 1 along thecircumferential edge of the port and forms a second stopper 9. Thisconcerns consequently a folded stopper.

[0072] A folded stopper ring 8, 9 is illustrated in FIG. 7D in acorresponding manner to FIG. 7C, however the regions 2A or 2C of thestopper 8, 9 directly adjacent to the profiling, designated here with2B, of the layer 1 being profiled likewise in a similar manner to thelayer 1 in the profiling region 2 b and thus abutting on both sidesagainst the profiling 2 b in a form fit. This consequently concerns herealso a profiled folded stopper.

[0073] In further examples, both the amplitude and the spacing of theindividual wave crests can be varied not only within the profiling 2 b,either along the circumferential edge of the port or also in aperpendicular direction to the circumferential edge of the port, butalso the profiled regions 2A and 2C can in a similar manner have aprofiling with different amplitudes and wave spacings. In particularwave crests between the individual layers at adjacent places can deviatefrom each other. Thus the profiling 2 a and 2 c in FIGS. 7B and 7D canhave wave crest heights or wave crest spacings at points adjacentrespectively to the profiling 2 b which are different from the latter.By corresponding choice of amplitudes and periods of the profiling inthe individual layers and stopper rings, a specific influencing of thedeformation limitation and of the elastic properties of the flat gasketdirectly adjacent to the port is possible.

[0074] In FIG. 8, an embodiment is now shown in which the profiling 2 isformed in the shape of a trapeze. The trapeze comprises accordinglyuniform trapezes which are disposed in a row. In the embodiment of FIG.8a, an edge angle is provided which can be between 0 and 30 degrees.FIG. 8b shows a further embodiment in which the trapezoidal profiling 2is adjacent to a bead 3. It is essential in the embodiments according toFIGS. 8b and 8 c and 8 d that the profiling 2 in its amplitude, i.e. inthe profile height, and the spacing of the wave crests from each other(periods) differ clearly from the profiling of the bead 3. The profileheight of the profiling is accordingly half or less than that of thebead 3.

[0075] The embodiment of FIGS. 8b and 8 d are formed comparably withrespect to the profiling 2 and the bead 3. The FIG. 8c shows a two-layervariant, each of the two layers having an identical profiling. Incontrast, an embodiment is also possible in which only one of the twoactive layers as here in 8 d the lower layer—shows the profilingaccording to the invention.

[0076] Whichever of the corresponding embodiments are chosen dependsupon the respective purpose of use, i.e. upon the conditions for whichthe gasket is provided.

[0077] A particular advantage of the embodiments according to theinvention according to FIG. 8 can be seen in the fact that, byflattening the wave crests and wave troughs, i.e. by forming a trapezefor the profiling, better sealing conditions are achieved, whichobviously can be attributed to the fact that this embodiment leads tosignificantly reduced recesses on the top and/or block side.

[0078]FIG. 9 shows a further embodiment of the profiling 2. Only theprofiling is shown in the embodiment according to FIG. 9. This profiling2 can be disposed once again, as also shown in FIGS. 8a to 8 d, adjacentfor example to a bead and be disposed in one, two or three layerconcepts.

[0079] The advantage of the embodiment according to FIG. 9 can be seenin the fact that here a radius-swaged undulating bead is used, i.e. aprofiling, in which the undulation has been swaged in the crests andtroughs so that the result is material strengthening at the edges. Thisembodiment is distinguished by a particularly good behaviour withrespect to recessing on the cylinder in a block and/or top side. Theadvantage of this variant can also be seen in the fact that the elasticbehaviour can once again be set specifically by the degree of swaging.According to whether the material thickening in the edges is more orless reinforced with respect to the embodiment according to FIG. 8, thisleads to a change in the elastic behaviour. In FIG. 9 a correspondingdimensioning is indicated in order to clarify the plastic deformation.

[0080] The embodiment according to FIG. 9 has proved to be particularlypreferred.

1. Flat gasket having at least one metallic layer in which at least oneport is formed, characterised in that the metallic layer or at least oneof the metallic layers (1) is formed at least in regions in the form ofan undulating- and/or serrated profiling (2) around the port(s).
 2. Flatgasket according to claim 1, characterised in that the profiling (2) isformed with at least one period in the metallic layer(s) (1).
 3. Flatgasket according to claim 1 or 2, characterised in that a bead (3) isformed around the port(s) in the metallic layer (1), in which theprofiling (2) is configured, adjacent to the profiling and the profiling(2), which is disposed at least on one side adjacent to the bead (3),forms a deformation limiter for the bead (3).
 4. Flat gasket accordingto one of the preceding claims, characterised in that, in a furthermetallic layer, a further undulating and/or serrated profiling is formedat least in regions around the port, both profilings being disposed, atleast in regions, directly one on top of the other.
 5. Flat gasketaccording to the preceding claim, characterised in that the twoprofilings have different spacings of the wave crests or teeth, adifferent profile height (amplitude) and/or different radii of curvatureof the waves.
 6. Flat gasket according to one of the preceding claims,characterised in that, in a further metallic layer (1′), at least onebead (3) is formed around the port(s), and the profiling (2), which isdisposed in the adjacent metallic layer (1) at least on one side in theplane of the layer adjacent to the bead, forms a deformation limiter forthe bead (3).
 7. Flat gasket according to one of the preceding claims,characterised in that a further layer is adjacent to the layer in whichthe profiling is formed, said further layer being profiled in acorresponding manner with the same profile height (amplitude) or with adifferent profile height therefrom and/or the same spacing of the wavecrests or teeth (period) or a spacing which is different therefrom. 8.Flat gasket according to one of the preceding claims, characterised inthat a metal ring is disposed as a stopper, at least in regions, on thelayer in which the profiling is formed, in the region of the profiling,at least partly along the circumference of the port.
 9. Flat gasketaccording to the preceding claim, characterised in that the metal ringis crimped over along the port around the metallic layer with profilingand forms an upper and lower stopper with respect to the layer.
 10. Flatgasket according to one of the two preceding claims, characterised inthat the metal ring is profiled on one or both sides of the metalliclayer in a corresponding manner with the same profile height (amplitude)or a profile height which is different therefrom and/or the same spacingof the wave crests or teeth (period) or a spacing which is differenttherefrom.
 11. Flat gasket according to one of the preceding claims,characterised in that the profile height (amplitude) and/or the spacingsof the wave crests or teeth are different within the profiling (2). 12.Flat gasket according to one of the preceding claims, characterised inthat the wave crests and/or troughs are flattened out.
 13. Flat gasketaccording to claim 12, characterised in that the profiling istrapezoidal.
 14. Flat gasket according to one of the preceding claims,characterised in that the profiling (2) of the wave is plasticallydeformed in regions and/or in part.
 15. Flat gasket according to one ofthe preceding claims, characterised in that the profiling is swaged inthe form of a wave in the region of the side so that a tapering ispresent in comparison to the wave crests and/or troughs.
 16. Flat gasketaccording to one of the preceding claims, characterised in that theprofiling is swaged in the form of a wave in the region of the crestsand/or troughs so that a tapering is present in comparison to the side.17. Flat gasket according to one of the preceding claims, characterisedin that, within the profiling (2), at least partly and/or in regions afiller material, for example an elastomer, is contained.
 18. Flat gasketaccording to the preceding claim, characterised in that the fillercontent of the profiling with filler material is of varying quantitywithin the profiling (2).
 19. Flat gasket according to one of the twopreceding claims, characterised in that the filler content of theprofiling with filler material within the profiling (2) is of varyingquantity over the circumference.
 20. Flat gasket according to one of theclaims 11 to 19, characterised in that the filler content of theprofiling with filler material within the profiling (2) is of varyingquantity around the port from the interior towards the exterior. 21.Flat gasket according to one of the preceding claims, characterised inthat the number of waves or teeth is of varying quantity in differentregions of the circumference around a port.
 22. Flat gasket according toone of the preceding claims, characterised in that the profile heightsand/or the spacings of the wave crests or teeth of the profiling (2) areof varying size in different regions of the circumference around a port.23. Flat gasket according to one of the preceding claims, characterisedin that at least the layer (1), in which the profiling is formed, ismade of spring steel.
 24. Flat gasket according to one of the precedingclaims, characterised in that at least the layer, in which the profilingis formed, is made of a cold deformable steel which hardens duringtempering.
 25. Flat gasket according to one of the preceding claims,characterised in that webs are present between the teeth or in the wavetroughs of the profiling.
 26. Flat gasket according to one of thepreceding claims, characterised in that the wave crests and the wavetroughs or teeth are flattened and/or smoothed.
 27. Flat gasketaccording to one of the preceding claims, characterised in that theregion between adjacent wave crests and wave troughs or between teeth,which are adjacent to each other and disposed on different sides of thelayer, has a smaller material thickness than the wave crests/-troughs orteeth.
 28. Flat gasket according to one of the preceding claims,characterised in that the wave crests/-troughs or teeth, which aredisposed on different sides of the layer, have a different conformation,for example height, spacing, shape and the like and/or materialthickness.
 29. Method for the production of a flat gasket according toone of the preceding claims, characterised in that an undulating and/orserrated profiling (2) is impressed in at least one metallic layer (1)at least in regions around one or more port(s).
 30. Method according toclaim 29, characterised in that the impressed profiling (2) is planishedat least in regions.
 31. Method according to claim 30, characterised inthat the metallic layer (1) is braced during the planishing.